BLAT however doesn't seem to do SSL-encrypted authentication, so I'm still with my previous solution.

I'm surprised a client can connect to a host on a hibernating server. You mentioned wake-up-on-LAN, but I'd have expected the client to time-out by then. I don't think I can help with the hibernation thing; minimised Dom2 hosts with no client connections do seem to regularly show small amounts of CPU use. CPU use resets the inactivity timer for Standby and Hibernation, and that's that really.

One kludgy option would be to script or schedule hibernations at regular intervals. But that doesn't sound good even as I type it. Hmm...